#include <stddef.h>
struct test {
    int a;
    char b;
    int c;
};
extern int copy_to_user(void *dest,void *src,size_t size);
void do_stuff(void *usr_buf){
    struct test arg = {.a = 1,.b = 2,.c = 3};
    copy_to_user(usr_buf,&arg,sizeof(arg));
}